stars - PowerPoint PPT Presentation

Loading...

PPT – stars PowerPoint presentation | free to download - id: 65bef9-Yzk2Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

stars

Description:

The Wonder And Beauty Of: Stars: The View From Earth Constellation: a group of stars that (from Earth) resembles a recognizable form Astronomers have officially ... – PowerPoint PPT presentation

Number of Views:19
Avg rating:3.0/5.0
Slides: 20
Provided by: Stri69
Learn more at: http://science1d.wikispaces.com
Category:
Tags: main | sequence | star | stars

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: stars


1
stars
  • The Wonder And Beauty Of

2
Stars The View From Earth
  • Constellation a group of stars that (from Earth)
    resembles a recognizable form
  • Astronomers have officially listed a total of 88
    constellations can you name any?
  • e.g. Ursa Major, Cassiopeia, Orion, Pegasus,
    Sagittarius, Ursa Minor
  • Asterisms smaller recognizable star patterns
    within a larger constellation
  • e.g. Big Dipper, Little Dipper
  • Astronomical phenomenon any observable
    occurrence relating to astronomy

3
Stars The View From Earth
  • Constellations vary greatly in their distances
    from Earth
  • They appear to be twinkling because they are of
    similar brightness

4
Quick Lab Reading Star Charts
  • Use the handout to answer the following questions
    on your own.
  • In which constellation is Polaris ( the North
    Star) located?
  • What planet is shown in the constellation
    Capricornus?
  • Betelgeuse is a large star located in what
    constellation?
  • What is the name of the constellation that has
    three bright stars in a row?
  • What is the name of the star that seems to form
    the tail of the swan-shaped constellation known
    as Cygnus?
  • Is the star Aldebaran located east or west of
    Betelgeuse?
  • What is the name of the star cluster located
    midway between the constellations of Taurus and
    Perseus?
  • What large star seems to form the right foot of
    the constellation commonly referred to as Orion
    the Hunter?

5
Quick Lab Answers
  • In which constellation is Polaris ( the North
    Star) located?
  • It is located in Ursa Minor or the Little Dipper.
  • What planet is shown in the constellation
    Capricornus?
  • Venus is shown in the constellation Capricornus.
  • Betelgeuse is a large star located in what
    constellation?
  • It is located in the constellation Orion.
  • What is the name of the constellation that has
    three bright stars in a row?
  • Its name is Orion.

6
Quick Lab Answers
  • What is the name of the star that seems to form
    the tail of the swan-shaped constellation known
    as Cygnus?
  • The name of the star is Deneb.
  • Is the star Aldebaran located east or west of
    Betelgeuse?
  • Aldebaran is located west of Betelgeuse.
  • What is the name of the star cluster located
    midway between the constellations of Taurus and
    Perseus?
  • The name of the star cluster is Pleiades.
  • What large star seems to form the right foot of
    the constellation commonly referred to as Orion
    the Hunter?
  • Rigel is the large star forming the right foot of
    Orion.

7
A Star Is Born
  • Life span of stars is VERY LONG
  • Stars are formed from a collapsing nebula
  • Caused by
  • Gravitational attraction of a nearby star
  • Shockwave from an exploding star
  • Region with greatest amount of matter starts to
    draw material towards it using gravity ? star
    forms here
  • Star begins to spin from energy of material
    coming in
  • High pressures build up, heating up atoms, star
    glows
  • Protostar star in the first stage of formation

8
A Star Is Born
  • Eventually, temperature rises to millions of
    degrees Celsius
  • Nuclear reactions starts
  • Takes thousands of years for energy from the core
    to reach the stars outside
  • When this finally happens, the star begins to
    shine!!

9
Life Cycle of Stars
  • 100 years ago, we knew that different kinds of
    stars existed
  • We didnt know that they had a life cycle like us
  • How a stars evolves in its lifetime depends on
    the mass it had when it was originally formed
  • Three general mass categories
  • Low mass
  • Medium mass
  • High mass
  • Different masses have different lives!!

10
Low Mass Stars
  • Use their nuclear fuel much more slowly
  • Can last for 100 billion years
  • 8X longer than the universes age right now!!
  • Less gravity and pressures than other stars
  • Shine weakly as small red stars called red dwarfs
  • Light starts dim and gradually gets dimmer
  • Get cooler and turns into a white dwarf
  • They collapse under own gravity and burn out
  • Most stars in our universe are red dwarfs!!

11
Medium Mass Stars Like Our Sun
  • Burn nuclear fuel faster than red dwarfs
  • Takes about 10 million years to use up their fuel
  • For those 10 million years, star is quite stable
  • Hydrogen fuel begins to run out
  • Star collapses under own gravity like white dwarf
  • Collapsing raises temp and pressure again in star
  • This causes fusion of helium
  • He accumulated at the core of the star
  • This reignites the star
  • But as core heats up, stars expands quickly into
    a red giant
  • e.g. Aldebaran
  • Eventually, He burns out and star collapses,
    slowly burning out like white dwarf

12
High Mass Stars
  • These are more than 10 times the mass of Sun
  • Gravity makes nuclear reactions accelerate
  • Makes star hotter, brighter, and bluer
  • Always will explode
  • Hydrogen is used up in less than 7 billion years
  • Star collapses like low and medium mass stars
  • Compression causes He to fuse
  • VERY HIGH temps cause star to expand into a
    supergiant
  • e.g. Polaris, Betelgeuse
  • When He fuel runs out, collapses again
  • Process repeats many times ? new elements like Fe
    are made

13
High Mass Stars What an Ending!!
  • If too much of core is made of Fe, star turns off
  • Star collapses one final time
  • The collapse is so fast and intense, star heats
    up to millions of degrees and EXPLODES
    (supernova)
  • All elements of periodic table were made this way
  • Explosion sends these heavy elements to space
  • Core thats left after this goes one of two ways,
    depending on the mass of the original star
  • Neutron Star
  • Black Hole

14
Neutron Stars
  • Star was between 10 and 40 times Suns mass
  • Supernovas explosion is outward and inward
  • Atoms at core compress and collapse, forming
    neutrons
  • When stars core is just a bunch of neutrons
    about 15 km across ? neutron star
  • Made of the densest material known

15
Black Holes
  • Star was more than 40 times Suns mass
  • After supernova, stars core is under so much
    gravitational force that nothing can stop its
    collapse
  • Not even formation of neutrons
  • Effect of gravity is so great that space, light,
    time, and other things all start to fall to a
    SINGLE POINT
  • They grow with the more stuff they pull in

16
Life Cycles of Stars
17
Hertzsprung-Russell Diagram
  • Differences between stars include
  • Colour
  • Brightness or Luminosity
  • Surface Temperature
  • 1919? Ejnar Hertzsprung and Henry Norris Russell
    sorted and plotted thousands of stars according
    to these characteristics
  • One of the most important discoveries in
    astronomy in the 20th century

18
Hertzsprung-Russell Diagram
  • Showed very clear relationships between star
    properties
  • Colour red on right, blue on left, yellow in
    between
  • Luminosity brightest at top, dimmest at bottom
  • Luminosity of 100 means 100 times brighter than
    our sun
  • Surface temp hottest on left, coolest on right

19
Hertzsprung-Russell Diagram
  • Patterns based on three star properties
  • Star data forms a distinct band from top L to
    bottom R
  • Called the main sequence ? sun is a main sequence
    star
  • These stars are thought to be in stable main part
    of their life cycle
  • Stars not along the main sequence are often near
    the end of their lives
  • White hot
  • Small ? dim
  • Red cool
  • Large ? bright
About PowerShow.com